Coronary angioplasty has been used as an alternative to coronary bypass surgery to open occluded coronary arteries supplying blood to the heart muscle. Balloon catheters have been used to perform the angioplasty procedure. In such a procedure, the balloon catheter is inserted into an artery and guided into a coronary artery to a portion of the coronary artery which has been at least partially occluded by deposits of plaque and thrombus on the artery wall. The balloon catheter is inflated at the occluded portion of the artery, opening the passageway. Ordinarily, the catheter is then removed from the artery.
The present invention is based upon the recognition that pieces of thrombus may form at anytime on the plaque.
When angioplasty is performed, the thrombus may dislodge and travel further into the artery, eventually causing blood clots or blockage in other portions of the artery. The thrombus may continue to form where the angioplasty was performed thus causing further blockage at the portion of the artery which was originally occluded. The present invention permits removal of thrombus from the artery, thereby lowering the risk of future blockage.
Techniques have been used to remove thrombus from arteries remote from the heart as for example in the femoral artery. In such a procedure, typically, the balloon catheter is withdrawn in its inflated state directly out of an artery, thus carrying and removing thrombus with it, and, because of the direction of the flow of blood, without any danger of the thrombus traveling to superior arteries. Because a coronary catheter is guided into a coronary artery by way of the aorta, attempting to remove the thrombus from a coronary artery simply by withdrawing an inflated balloon catheter would pose serious risks that the dislodged thrombus would be carried by the blood travelling through the aorta to the brain or other parts of the body, causing strokes or partial blockage of other arteries.
It is a primary objective of the present invention to provide a method and apparatus which would allow removal of dislodged thrombus from a coronary artery during a coronary angioplasty or thrombectomy procedure while significantly reducing the risk of carrying the thrombus into the bloodstream where as a result additional blockages, especially in the brain, may occur.
Generally, the coronary thrombectomy apparatus of the invention comprises a balloon catheter with an inflatable balloon at the distal end coupled to an inflator mechanism, and a coronary thrombectomy catheter fitting over the balloon catheter. The balloon catheter and the coronary thrombectomy catheter are arranged to be axially moveable with respect to each other. The distal end of the coronary thrombectomy catheter comprises a material that is sufficiently flexible so that it may be expanded when the inserted balloon of the balloon catheter is inflated, and also sufficiently rigid so that when the balloon of the balloon catheter is deflated, the distal end of the coronary thrombectomy catheter retains its expanded shape. The coronary thrombectomy catheter and balloon catheter may be used together to perform a coronary angioplasty procedure and to remove thrombus and/or plaque from a coronary artery.
Pursuant to a feature of the invention, the coronary thrombectomy catheter may comprise a polymer material such as polyurethane which is thinned at the distal end of the thrombectomy catheter.
In another embodiment, the coronary thrombectomy catheter may comprise a thinned polymer material such as polyurethane, which is covered with a reinforced coating, preferably of glass fibers, for the entire length of the catheter with the exception of the distal end of the thrombectomy catheter.
The balloon catheter which is inserted into the thrombectomy catheter may be inflated so that when it expands, the thinned distal end of the catheter also expands. The balloon catheter has the ability to be deflated, and reinflated. Following expansion of the coronary thrombectomy catheter, the balloon catheter may then be deflated and extended beyond the distal end of the coronary thrombectomy catheter into the artery. The balloon catheter may be guided into the occluded portion of the artery and used to perform an angioplasty procedure, i.e., inflating the balloon to open an occlusion of the artery. Pursuant to a feature of the invention, the balloon catheter would be used to carry thrombus or plaque out of the artery. The balloon is extended beyond the occluded portion, inflated and then retracted toward the expanded distal end of the thrombectomy catheter to dislodge and carry thrombus into the expanded distal end. The balloon catheter may be inflated to a size larger than the inner circumference of the expanded distal end of the coronary thrombectomy catheter so that when the balloon catheter is retracted into the coronary thrombectomy catheter, the balloon acts as a plug, closing the distal end of the coronary thrombectomy catheter and retaining the dislodged thrombus within the coronary thrombectomy catheter.
Generally, the coronary thrombectomy procedure of the invention comprises the steps of inserting a balloon catheter and a coronary thrombectomy catheter with an outer guide catheter into an artery; guiding the balloon catheter and the coronary thrombectomy catheter, within the guide catheter, to an entrance of a coronary artery; extending the coronary thrombectomy catheter and balloon catheter out of the guide catheter into the coronary artery; inflating the balloon catheter to expand the distal end of the coronary thrombectomy catheter; deflating the balloon, the distal end of coronary thrombectomy catheter retaining its expanded shape; optionally guiding the deflated balloon catheter into an at least partially occluded portion of the artery; optionally inflating, deflating, and/or manuevering the balloon as necessary to perform an angioplasty procedure; guiding the balloon catheter, the balloon being deflated, so that the balloon is situated downstream from thrombus and/or plaque which is to be removed; reinflating the balloon to a size at which the balloon may act to plug the open expanded distal end of the coronary thrombectomy catheter; retracting the inflated balloon catheter toward the coronary thrombectomy catheter to dislodge and withdraw thrombus and/or plaque from the artery, into the expanded distal end of the coronary thrombectomy catheter and thus retaining dislodged thrombus and/or plaque in the expanded distal end of the coronary thrombectomy catheter and utilizing the expanded balloon to plug the distal end of the coronary thrombectomy catheter; and thereafter removing the coronary thrombectomy catheter containing the balloon catheter and any thrombus or plaque.